#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <cmath>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <stdlib.h>
#include <stdio.h>
#include <bitset>
using namespace std;
#define FOR(I,A,B) for(int I = (A); I < (B); ++I)
typedef long long ll;

int main()
{
  ll A, B;
  cin >> A >> B;
  ll ans;
  if(A<B){
    ans = B - 2;
  } else {
    ans = 2e9 - B - 1;
  }
  cout << ans << endl;
  return 0;
}